The interaction between protostars and their environment: Carbon-bearing species towards low mass protostars

Department of Physics, UMIST, PO Box 88, Manchester M60 1QD, UK

Corresponding author: J. V. Buckle, j.buckle@jach.hawaii.edu

Received: 9 November 2000
Accepted: 10 September 2001

Abstract

It is clear that outflow activity can have a significant impact on the structure and evolution of material in protostellar environments, but the detailed nature of the interaction between the outflow and surrounding material is not clearly understood. To probe the impact of outflow activity on protostellar core material, in this paper we present observations of  ( 2_k),  ( 2) and DCN ( 1 multiplet) at 145 GHz towards a sample of Class 0 and Class I sources, to place constraints on the physical and chemical changes which have taken place through the onset of star formation. ₃ was detected towards all of the sources and positions observed. In many sources, the  lines have two velocity components: one broad ( 1.5 km s^-1), and one narrow ( 0.7 km s^-1). Both velocity components of  show significantly (>10) enhanced abundances relative to quiescent dark clouds. These two components are predominantly a feature of the Class 0 sources. These sources also have the broadest lines in both components. H was detected towards 87% of the sources observed and DCN was detected towards 66% of the sources observed. The narrowest detected component of  has similar linewidths to , and is detected towards only a small fraction of positions, implying that only a small number of sources contain undisturbed material. The degree of activity implied by the enhanced abundances in  is larger in the Class 0 sources than the Class I sources. Since the narrower linewidth components also show enhanced abundances in this molecule, we conclude that energetic activity during the star formation process, which may include both outflow and infall processes, affects the apparently quiescent core material very early in the star formation process.